I appear to have this same truncation issue.
I am using MySQL 5.1.31 via TCP and MyDAC 5.80.0.46 for Delphi.
When I use TMyQuery to run 'SHOW SLAVE STATUS;' fields such as Last_IO_Error are reported as having a length of 20. This is true wether the fields are bound at designtime or runtime. Even if I use the field editor to increase the SIZE property of the field only the first 20 characters are returned.
Is there a workaround / known fix for this that I can apply ?
Best regards,
Damien.